9th chords similar to other compound chords?

[silvaone]

Im not a master of theory and I teand to work things out in my head.... recently I have really been coming to grips with chords and scales and my skill of sight playing (chords wise) has increased 10 fold....

I recently figured out that 9th chords (C9 for example... Bb D E G (C in treble clef)) have their inherent dominant 7ths in them.... now I dont understand why this is but I have been able to comfortably move around 9th chords for a long time because of my preferred style of playing (blues)....

Learning this has helped me to determine maj9th chords etc. which is all good !!

My question is what does the dominant 7th have to do with a 9th chords and does this mean that all chords past 9th (11th's and 13th's etc.) have to have the dominant 7th from the same root note scale/chord within them.... or is it just 9th chords? thank you

Silva

[Bob]

I think if it's "plain" then it's dominant.  C9, C11, C13

If they meant Major or minor, they would put Maj or min in there.  CMaj9, CMaj11, CMaj13.   

However, I think after 9ths, things get more complicated.  They don't always write them out like that -- that simple to read.  You end up with C9#11 for example.

That's for the written part.  The chord symbols.  I'm not a jazz expert.


I'm not quite sure what you're asking after that.

If you start stacking thirds up on the fifth step of the major scale, you'll get some type of dominant chord.  V, V7, V9, etc.

You just add another third on top of a seventh chord to get a ninth.  You can have a ninth chord built on any step of the scale (I think). 

I believe the main types are dominant, major, and minor ninth chords.

However, you can alter those notes.  Raise or lower them a half step.  So, you could end up with an altered dominant ninth.... V7b9.

Which leaves a lot of possibilities for chords up there.

And then with the 13th's, they can be easier to understand in terms of two chords, one on top of the other.  D7/C for example instead of C13#11.

I know with 11th's you're supposed to watch out for the m9 dissonance and treat that carefully when voicing -- like making a #11 instead of plain 11.

[preludium]

I recently figured out that 9th chords (C9 for example... Bb D E G (C in treble clef)) have their inherent dominant 7ths in them.... now I dont understand why this is

The answer is straight forward. Chords in the usual sense are stacked thirds. A 9th chord has its name due to the fact that you stack thirds until you reach the 9th with respect to the root. You need five of them: 1 - 3 - 5 - 7 - 9. Now it depends on what you get along that way if you stay within one key. For simplicity let's stick to C major.

If you start with C you get C - E - G - B - D. The 7th C - B is major, so this is no dominant chord. Let's start with the 2nd note D: D - F - A - C - E. The 7th D - C is minor, but it still is no dominant chord, since the 3rd D - F is minor. The same happens when you start at E. When building a 9th chord on the F you get the same effect as in the first example. From G: G - B - D - F - A. There it is! Major 3rd G - H and minor 7th G - F.

In your example you used C - E - G - Bb - D and made a partial inversion by transposing E and G by one octave. From a harmonic point of view it still is the same chord. The set of notes you were using may have come from the key of F major. May have, because with 5 notes the key is under-determined. More likely you're dealing with blue notes, which don't fit into the tempered system, but you have no effect on the fine tuning on the piano so you play a minor 7th instead.

There are other things like suspended chords. If you have a suspended 9th chord you stack thirds only to a triad and leave out the next ones until you reach the goal, so in that case you drop the 7th.